1. Field of Invention
The present disclosure relates to hydraulic fracturing of subterranean formations. In particular, the present disclosure relates to methods and devices for reducing vibration during hydraulic fracturing of a subterranean formation.
2. Description of Prior Art
Hydraulic fracturing is a technique used to stimulate production from some hydrocarbon producing wells. The technique usually involves injecting fluid into a wellbore at a pressure sufficient to generate fissures in the formation surrounding the wellbore. Typically the pressurized fluid is injected into a portion of the wellbore that is pressure isolated from the remaining length of the wellbore so that fracturing is limited to a designated portion of the formation. The fracturing fluid slurry, whose primary component is usually water, includes proppant (such as sand or ceramic) that migrate into the fractures with the fracturing fluid slurry and remain to prop open the fractures after pressure is no longer applied to the wellbore. Sometimes, nitrogen, carbon dioxide, foam, diesel, or other fluids are used as the primary component instead of water. A typical hydraulic fracturing fleet may include a data van unit, blender unit, hydration unit, chemical additive unit, hydraulic fracturing pump unit, sand equipment, wireline, and other equipment.
Traditionally, the fracturing fluid slurry has been pressurized on surface by high pressure pumps powered by diesel engines. To produce the pressures required for hydraulic fracturing, the pumps and associated engines have substantial volume and mass. Heavy duty trailers, skids, or trucks are required for transporting the large and heavy pumps and engines to sites where wellbores are being fractured. Each hydraulic fracturing pump usually includes power and fluid ends, seats, valves, springs, and keepers internally. These parts allow the pump to draw in low pressure fluid (approximately 100 psi) and discharge the same fluid at high pressures (up to 15,000 psi or more). The diesel engines and transmission which power hydraulic fracturing units typically generate large amounts of vibrations of both high and low frequencies. These vibrations are generated by the diesel engine, the transmission, the hydraulic fracturing pump as well as the large cooling fan and radiator needed to cool the engine and transmission. Low frequency vibrations and harshness are greatly increased by the large cooling fans and radiator required to cool the diesel engine and transmission. In addition, the diesel engine and transmission are coupled to the hydraulic fracturing pump through a u-joint drive shaft, which requires a three degree offset from the horizontal output of the transmission to the horizontal input of the hydraulic fracturing pump. Diesel powered hydraulic fracturing units are known to jack and jump while operating in the field from the large amounts of vibrations. The vibrations may contribute to fatigue failures of many differed parts of a hydraulic fracturing unit. Recently electrical motors have been introduced to replace the diesel motors, which greatly reduces the noise generated by the equipment during operation. Because of the high pressures generated by the pumps, and that the pumps used for pressurizing the fracturing fluid are reciprocating pumps, a significant amount of vibration is created when pressurizing the fracturing fluid. The vibration transmits to the piping that carries the fracturing fluid and its associated equipment, thereby increasing probabilities of mechanical failure for the piping and equipment, and also shortening their useful operational time.